20,934 research outputs found
XMM Follow-Up Observations of Three Swift BAT-Selected Active Galactic Nuclei
We present XMM-Newton observations of three AGN taken as part of a hunt to
find very heavily obscured Compton-thick AGN. For obscuring columns greater
than 10^25 cm^-2, AGN are only visible at energies below 10 keV via
reflected/scattered radiation, characterized by a flat power-law. We therefore
selected three objects (ESO 417-G006, IRAS 05218-1212, and MCG -01-05-047) from
the Swift BAT hard X-ray survey catalog with Swift X-ray Telescope XRT 0.5-10
keV spectra with flat power-law indices as candidate Compton-thick sources for
follow-up observations with the more sensitive instruments on XMM-Newton. The
XMM spectra, however, rule out reflection-dominated models based on the
weakness of the observed Fe K-alpha lines. Instead, the spectra are well-fit by
a model of a power-law continuum obscured by a Compton-thin absorber, plus a
soft excess. This result is consistent with previous follow-up observations of
two other flat-spectrum BAT-detected AGN. Thus, out of the six AGN in the
22-month BAT catalog with apparently flat Swift XRT spectra, all five that have
had follow-up observations are not likely Compton-thick. We also present new
optical spectra of two of these objects, IRAS 05218-1212 and MCG -01-05-047.
Interestingly, though both these AGN have similar X-ray spectra, their optical
spectra are completely different, adding evidence against the simplest form of
the geometric unified model of AGN. IRAS 05218-1212 appears in the optical as a
Seyfert 1, despite the ~8.5x10^22 cm^-2 line-of-sight absorbing column
indicated by its X-ray spectrum. MCG -01-05-047's optical spectrum shows no
sign of AGN activity; it appears as a normal galaxy.Comment: 18 pages including 4 figures, accepted by Ap
Correlations of the IR Luminosity and Eddington Ratio with a Hard X-ray Selected Sample of AGN
We use the SWIFT Burst Alert Telescope (BAT) sample of hard x-ray selected
active galactic nuclei (AGN) with a median redshift of 0.03 and the 2MASS J and
K band photometry to examine the correlation of hard x-ray emission to
Eddington ratio as well as the relationship of the J and K band nuclear
luminosity to the hard x-ray luminosity. The BAT sample is almost unbiased by
the effects of obscuration and thus offers the first large unbiased sample for
the examination of correlations between different wavelength bands. We find
that the near-IR nuclear J and K band luminosity is related to the BAT (14 -
195 keV) luminosity over a factor of in luminosity ()and thus is unlikely to be due to dust. We also find that the
Eddington ratio is proportional to the x-ray luminosity. This new result should
be a strong constraint on models of the formation of the broad band continuum.Comment: accepted to ApJ
Optical and X-ray Properties of the Swift BAT-detected AGN
The Swift Gamma-Ray Burst satellite has detected a largely unbiased towards
absorption sample of local () AGN, based solely on their
14--195 keV flux. In the first 9 months of the survey, 153 AGN sources were
detected. The X-ray properties in the 0.3--10 keV band have been compiled and
presented based on analyses with XMM-Newton, Chandra, Suzaku, and the Swift XRT
(Winter et al. 2009). Additionally, we have compiled a sub-sample of sources
with medium resolution optical ground-based spectra from the SDSS or our own
observations at KPNO. In this sample of 60 sources, we have classified the
sources using standard emission line diagnostic plots, obtained masses for the
broad line sources through measurement of the broad H emission line, and
measured the [OIII] 5007\AA luminosity of this sample. Based on continuum fits
to the intrinsic absorption features, we have obtained clues about the stellar
populations of the host galaxies. We now present the highlights of our X-ray
and optical studies of this unique sample of local AGNs, including a comparison
of the 2--10 keV and 14--195 keV X-ray luminosities with the [OIII] 5007\AA
luminosity and the implications of our results towards measurements of
bolometric luminosities.Comment: 4 pages, 2 figures, to appear in proceedings for 'X-ray Astronomy
2009', Bologna 09/2009, AIP Conference Series, Eds. A. Comastri, M. Cappi, L.
Angelin
Optical measurement of heteronuclear cross-relaxation interactions in Tm:YAG
We investigate cross-relaxation interactions between Tm and Al in Tm:YAG
using two optical methods: spectral holeburning and stimulated echoes. These
interactions lead to a reduction in the hyperfine lifetime at magnetic fields
that bring the Tm hyperfine transition into resonance with an Al transition. We
develop models for measured echo decay curves and holeburning spectra near a
resonance, which are used to show that the Tm-Al interaction has a resonance
width of 10~kHz and reduces the hyperfine lifetime to 0.5 ms. The antihole
structure is consistent with an interaction dominated by the Al nearest
neighbors at 3.0 Angstroms, with some contribution from the next nearest
neighbors at 3.6 Angstroms.Comment: 13 pages, 9 figure
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